"Anybody know who that is?" he asks, as an inflatable orange Zodiac speeds within range. When the Kiwis beat the US to win the Cup in 1995, they vowed to clean up what had become a game of relentless espionage among teams. Now "persistent observation" of another team's boats is explicitly forbidden until two months before the first races. The team bases in Auckland are patrolled by security guards and closed-circuit cameras; photographs anywhere within a team's compound are verboten; and when 65 and 67 are withdrawn from the water each night, their hulls and keels are shrouded by gray skirts. "Every team is curious about what the other is doing," Kaiko says. "You try to psych them out, to make them feel like they can never do anything without being watched."

Eventually, attention on the boat returns to 65 and 67, whose sensors and strain gauges are tracking 200 different parameters every second and sending the information across OneWorld's LAN to its chase boats and offices. Then the info gets dumped into a Microsoft SQL database, where it's sifted to pinpoint the effects of sail and hardware experiments. Unraveling all the input is, in the words of OneWorld engineer Richard Karn, "nearly impossible." Take the keel's trim tab, an adjustable surface that's analogous to the flap on an airplane wing. Simply finding the optimum trim settings for each wind speed requires comparing each flap setting against all others, using one boat as a control. The combination of settings and wind speeds is mind-boggling.

Making a sailboat fast is unlike making any other kind of vehicle fast. Cars and airplanes, for instance, operate within a single medium, but a boat plows through air and water, creating what's known as "free surface" between the two that dramatically raises drag. Every parameter of a Formula One car can be targeted and modeled, including the track on which it's racing. Airplanes can be so well modeled that some engineers even argue against building prototypes. And cars and planes are all powered by engines with precisely known and controllable horsepower. "Our power comes from the wind," says Kaiko, settling down once again at his laptop, as we roll gently in the swell. "It's variable in height, speed, direction, and density, and it's totally erratic and random." Ditto the track on which they race  waves and currents. And the yachts require not one pilot but 16 crewmen, each of whom is an independent variable.

OneWorld's designers began hammering out hulls almost immediately after the 2000 Cup. Unlike yachts in races between identical sailboats, the International America's Cup Class yachts are created around a complex formula that lets designers trade off sail area for length and weight. The formula has been the same since 1992, so making a boat faster than your competitors takes ever more powerful technology for even the smallest improvement. "Yet, if you can make your boat even a fraction of a second faster," says OneWorld designer Bruce Nelson, "that'll give your team the edge it needs. So the question is, How do you find that?" He answers himself: "If you really want to explore a boat, you need to run a 200-point matrix, and each point has to go through up to 100 iterations, so running one hull might take a day or two." OneWorld worked through hundreds of possible hulls to find this year's shape, a design as closely guarded as the curves on the Pentagon's stealth aircraft. "In '92, we looked at dozens of hulls, but none had this one's accuracy and sophistication," Nelson says. "Much more physics has been added: Now you can predict the performance down to a hundredth of a knot." Oracle, for its part, riffled through thousands of hull configurations on a Compaq AlphaServer SC supercomputer.

But tactical decisions intrude on what otherwise might seem a straightforward analysis: Do you want a hull that functions better upwind or downwind? Primed for 15 knots or 8? Less drag or more stability? "There are so many trade-offs that you have to be really smart," Kaiko says. The penalties for erring are high, only the least of which is ending up with a slow boat. "The wind loads on the rigging and hull are huge," says Kaiko, "and they're predicted, not known, so equipment breaks and people get hurt." In the 2000 race, the Australian yacht (designed by Kaiko) broke in half midrace. So far this year, two of Oracle's training boats have lost keels, and OneWorld lost a mast. Dennis Conner's boat, Stars & Stripes, sank.

After 10 minutes of straight-line sailing, 65 is two lengths ahead of 67. A decisive victory for the radically new rag, I suggest. "Maybe," Kaiko says, checking the numbers flowing in. "The winds are really too light and shifty, the data too inconsistent."

Suddenly there's the Zodiac again. The radio crackles, and in seconds the sail comes down and a more conventional one goes up; then another test begins. So it goes for the next eight hours, as the 65 and 67 race each other using various combinations of sails, and the data pours in. Every few minutes a crew member snaps photos of the sail from digital cameras mounted on the deck, to be scrutinized later. Periodically, sailors swap boats, to better distinguish between a yacht's performance and that of its crew. Ideally, over the course of the day, speed advantages can be traced to one particular sail, which can be tweaked yet again. Over months, the fastest permutations of sails and trim will be studied. Conclusive data is hard to come by, however. During any given moment of any particular test, the vessels weren't even sailing in the same wind despite being a mere hundred yards apart.

"It's a statistical process," says Katori, the team's lead programmer, as we take the boats in tow and head back to shore at the end of the day. "You have to build a lot of very subjective data before it begins to mean anything, and that's especially true in light wind. But over time you do build real numbers."